1. Technical Field
The present invention relates to a toner for developing an electrostatic charge image and a method for manufacturing the same, and an electrostatic charge image developer, a process cartridge and an image forming apparatus.
2. Related Art
Many methods for electrophotography are known. Generally, a latent image is formed, using various methods, on a photoreceptor (image holding member) using a photoconductive substance, the formed latent image is developed using a toner for electrostatic charge image development (hereinafter, sometimes referred to as “toner”) to form a toner image, then the toner image on the photoreceptor surface is transferred to a surface of a transfer body such as paper optionally using an intermediate transfer body, and the transferred image is pressurized, or heated and pressurized, to fix the toner image, or the transferred image is fixed by solvent evaporation, thereby forming the fixed image. The toner remaining on the photoreceptor surface is usually cleaned by various methods, as necessary, before being subjected again to the above processes.
As a fixing technique for fixing a transfer image which has been transferred onto the surface of a transfer body, a heat roll fixing method is generally known, wherein a transfer body, onto which a toner image has been transferred, is inserted between a pair of rolls including a heat roll and a pressure roll followed by fixing the toner image. Further, as a similar technique, a fixing method in which one or both of the rolls is replaced with a belt is also known. In these techniques, compared to other fixing methods, a fixed image is obtained quickly, and energy efficiency is high, and moreover, there is less damage to the environment by volatilization of a solvent or the like.
In the above toner obtained by the aggregation and coalescing method, it is known that good image formation is attainable by lowering the fixing temperature of the toner using a binder resin containing a crystalline resin and a non-crystalline resin.
However, in the production of the toner containing a crystalline polyester resin by the above aggregation/coalescing method, since the resin particles in a crystalline polyester resin dispersion readily aggregate compared to a non-crystal line polyester resin dispersion, the crystalline polyester resin readily aggregates by itself at an early stage when forming aggregated particles in the production of the toner, and, as a result, toner particles having an uneven composition (that is, having a phase separated structure in the order of several tens of nm to several hundreds of nm) are readily formed.
The unevenness in the toner composition entails broader toner charge distribution, and as a result, the charge distribution is magnified and fog worsens, and problems such as staining in a machine due to the generation of a toner cloud frequently occur. In particular, under a high temperature and high humidity environment, the influence of the unevenness of the toner composition becomes remarkable.